Settings: Add an option to force pre-O apps to use full screen aspect ratio

When an app target pre-O releases, the default max aspect ratio
is 1.86:1 which leads to ugly black areas on devices that have
screens with higher aspect ratio (for example Galaxy S8/S9).

This change adds an option to allow users to change aspect ratio
for pre-O apps to full screen aspect ratio.

Change-Id: I0fb73511cf654ee22a4cfb7aef252008f8db8855